1. Field of the Invention
The present invention relates to a sheet supplying apparatus for supplying a sheet, an image reading apparatus utilizing such a sheet supplying apparatus to supply a sheet original to a reading portion, and an image recording apparatus utilizing such a sheet supplying apparatus to supply a sheet to a recording portion.
2. Related Background Art
There has been proposed a sheet supplying apparatus comprising a sheet stacking portion on which sheets are stacked, a supply roller for supplying the sheets stacked on the sheet stacking portion, a feed roller disposed at a downstream side of the supply roller and rotated in a normal direction with respect to a sheet supplying direction, and a reverse rotation roller capable of being urged against the feed roller and rotated in a reverse direction. Further, it is also known to provide a sheet supplying apparatus including a continuous supply mode for continuously supplying sheets stacked on a sheet stacking portion and manual sheet insertion mode for supplying a sheet rested on the sheet stacking portion one by one.
In the continuous supply mode, the sheets stacked on the sheet stacking portion are successively supplied between the downstream feed roller and reverse rotation roller by the supply roller, where lower sheets other than an uppermost sheet among double-fed sheets are returned toward an upstream direction by the reverse rotation roller, and only the uppermost sheet contacted with the feed roller is separated from the other sheets and is conveyed toward a downstream direction.
On the other hand, in the manual sheet insertion mode, as is in the continuous supply mode, when the sheet is supplied between the feed roller and the reverse rotation roller, if the sheet has poor resiliency (such as a thin sheet), a tip end of the sheet will be entrained by the reverse rotation roller or winkles are apt to be formed in the sheet. Further, when a folded sheet is supplied, since the reverse rotation roller tries to separate a lower folded portion of the sheet from an upper folded portion of the sheet, thereby causing the sheet jam. Thus, to avoid such an inconvenience, the reverse rotation roller is separated from the feed roller so that the sheet is supplied toward the downstream direction by the feed roller alone.
However, in the manual sheet insertion mode, when the reverse rotation roller is separated from the feed roller, although the entrainment of the sheet on the reverse rotation roller and the formation of the wrinkles can be prevented, a contacting force between the feed roller and the sheet becomes small, a conveying force acting on the sheet frequently becomes insufficient.